Connectors have been developed for use in medical instruments in a variety of ways. For example, connectors may be used to connect a medical instrument to a source of power or information used by the instrument. Connectors may also join subsystems within the instrument and couple the instrument to external systems that respond to the instrument's output. The types of connections provided by the connectors are most commonly electrical and/or mechanical.
A variety of styles of connectors are used in medical instruments. The particular style selected is often a function of a number of factors. For example, in certain applications, the connector must allow connections to be made and broken quickly and easily, with minimal human involvement. In other applications, it is more important to ensure that a secure connection is produced, providing good electrical contact between the connected components and minimizing the possibility of mechanical separation.
In one particular application of interest, a pair of connectors are rigidly mounted in the battery tray of a medical instrument to engage hollow cylindrical terminals provided adjacent one end of a battery pack. Each connector includes a conductive post having a radially compressible "banana" end that projects out of the instrument, and a threaded end that projects into the instrument. The banana ends are designed to be received and radially compressed by the battery pack terminals, while the threaded ends are connectable to the internal wiring of the instrument by ring terminals and nuts.
The battery pack is connected to the instrument in the following manner. Although the path followed by the battery pack as it is inserted into the tray may vary somewhat, it generally includes two components. First, the battery pack is moved in a plane defining an acute angle with respect to the tray, as the end of the battery pack opposite the terminals is inserted into the battery tray. Second, the battery pack is rotated slightly, moving the battery pack terminals into engagement with the banana ends of the connectors.
In practice, the battery pack is inserted with a single sweeping motion that includes both of these components. While this motion allows the battery pack to be quickly and easily connected to the instrument, the rotational component prevents the posts and terminals from being aligned at all times. Thus, stresses may be applied to the connector during insertion.
To reduce these stresses, the banana posts and the battery pack terminals are aligned at a slightly nonperpendicular angle to the battery tray and battery pack, respectively. If the battery pack terminals are considered to sweep an arc during insertion of the battery pack into the tray, the posts and terminals are roughly tangentially aligned to that arc. As a result, the posts and terminals remain relatively closely aligned during the entire insertion process, reducing the lateral force and, hence, stress applied to the posts.
Another feature of this connector relates to the protection of the inner circuits and systems of the instrument. By rigidly molding the connector into the housing of the instrument, an excellent seal is provided around the post, limiting the intrusion of moisture or particulate into the instrument. This can be particularly important when the instrument is designed to allow batteries to be changed in the field, where a variety of environments may be experienced.
In addition, in some instances it may be desirable to check internal connections made to the connector, or replace the connector entirely. With conventional connectors this may either be impossible or require access to the inside of the instrument, which can be inconvenient and time consuming. Thus, it would be helpful to allow this type of field service to be accomplished without requiring partial disassembly of the instrument.
It would also be desirable to provide a connector that offers a good seal between the battery pack and the connector, as well as between the interior and exterior of the instrument. Further, it would be helpful to develop a connector that makes removal of the battery pack from the tray easier. Finally, to decrease manufacturing costs, it would be useful to provide a connector that can be positioned on the housing within relatively loosely defined tolerances and still assure proper alignment of the connectors.